UNIVERSITY    OF    CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL    EXPERIMENT   STATION 

BERKELEY,    CALIFORNIA 


GRAFTING  AFFINITIES  WITH 
SPECIAL  REFERENCE  TO  PLUMS 

MYER  J.  HEPPNER  and  ROY  D.  McCALLUM 


BULLETIN  438 

November,  1927 


UNIVERSITY  OF  CALIFORNIA  PRINTING  OFFICE 

BERKELEY,  CALIFORNIA 

1927 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/graftingaffiniti438hepp 


GRAFTING  AFFINITIES  WITH  SPECIAL  REFERENCE  TO  PLUMS 

MYER  J.  HEPPNERi  and  ROY  D.  McCALLUM2 


No  deciduous  fruit  in  California  has  been  grafted  and  redrafted 
more  than  the  plum  including"  both  Japanese3  (Primus  salicina)  and 
European  (Primus  domestica)  varieties.  This  is  especially  true  in 
the  Sierra  foothill  region  and  in  the  Vaca  Valley  section,  two  of  the 
largest  plum  growing  districts  in  the  state.  Several  factors  have 
been  responsible  for  this  practice.  Of  chief  importance  has  been 
the  effort  to  reduce  the  number  of  varieties  and  eliminate  the  mediocre 
ones  which  for  years  have  seriously  affected  market  prices  for  plums. 

During  the  1924  Placer  County  Fruit  Growers'  Convention,  a 
committee4  appointed  to  select  the  varieties  of  plums  best  suited  to 
the  Sierra  foothill  region  recommended  17  out  of  the  55  varieties  then 
being  grown.  The  report  of  this  committee  summarized  in  the  form 
of  a  score  card  follows: 


Variety 

Size 

Yield 

Color 

Tree 
growth 

Selling 
price 

Shipping 
quality 

Total 

20% 

20% 

10% 

10% 

30% 

10% 

100% 

20 
20 
18 
20 
15 
15 
17 
10 
20 
13 
15 
18 
14 
8 
12 
12 
12 

18 
18 
15 
18 
14 
20 
20 
20 

5 
20 
13 
14 
20 

5 

10 
13 
10 

5 
5 

10 
5 

10 
7 
7 
7 
5 
7 
7 
7 
7 

10 
7 

10 

10 

8 
7 
6 
7 
8 
10 
5 
10 
10 
10 
10 
8 
6 
10 
10 
7 
3 

30 
30 
30 
27 
27 
23 
23 
23 
30 
20 
25 
20 
18 
27 
20 
15 
20 

10 
10 
10 
10 
10 
7 

10 
10 
10 
10 
8 
8 
9 
10 
10 
8 
8 

91 

90 

89 

87 

84 

82 

82 

80 

80 

80 

78 

75 

74 

70 

69 

65 

63 

In  order  to  concentrate  upon  these  relatively  few  varieties,  many 
growers  have  been  grafting  over  some  of  the  weaker  ones.  This  fact 
has  probably  accounted  for  most  of  the  plum  grafting  done  in  recent 


i  Research  Assistant  in  Pomology. 

2  Specialist  in  Agricultural  Extension. 

3  Throughout  the  text  the  term  Japanese  varieties  will  refer  to  true  Japanese 
varieties  and  their  hybrids. 

4  Committee  members :  J.  W.  Barnicott,  J.  H.  Andregg,  J.  E.  Van  Riper,  J.  A. 
Teagarden,  J.  J.  Brennan,  Lee  Rippey,  C.  K.  Turner,  and  R.  D.  McCallum. 


4  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

years.  Moreover,  some  varieties  have  proved  unsuitable  for  one  reason 
or  another,  to  certain  sections.  Rather  than  remove  the  trees  entirely, 
many  growers  have  resorted  to  grafting  in  order  to  secure  varieties 
which  are  better  adapted  to  their  particular  conditions. 

Top-working  for  pollination  purposes  constitutes  a  third  important 
factor  in  accounting  for  the  large  amount  of  this  grafting.  Cross 
pollination  is  of  prime  importance  for  the  setting  of  fruit  in  prac- 
tically all  plum  varieties.  It  has  been  necessary,  therefore,  to  intro- 
duce an  additional  variety  into  orchards  which  were  at  one  time  solid 
blocks  of  one  variety.  This  is  being  done  by  grafting-over  established 
trees  with  the  proper  pollinizing  variety. 

The  three  factors  mentioned  above,  as  being  instrumental  in  caus- 
ing the  large  amount  of  grafting  that  has  been  practiced  with  plums — 
first,  to  decrease  the  number  of  varieties ;  second,  to  secure  varieties 
better  adapted  to  certain  localities,  and  third,  to  bring  about  cross- 
pollination — have  brought  to  light  a  great  deal  of  information  regard- 
ing affinities  existing  not  only  among  different  plum  varieties  but 
also  between  plums  and  other  species  of  deciduous  fruits. 

Realizing  the  importance  of  a  knowledge  of  plum  affinities  to  the 
grower  contemplating  a  change  in  variety  for  one  reason  or  another, 
it  was  thought  advisable  to  bring  together  all  available  information  on 
the  subject.  Experiments,  the  results  of  which  are  not  ready  for 
publication,  are  now  under  way  at  the  College  of  Agriculture,  Davis, 
to  determine  this  question  in  a  quantitative  manner.  At  present, 
there  are  no  published  data  relative  to  California  varieties. 

The  information  contained  in  this  bulletin  is  not  primarily  the 
results  of  experiments  carried  on  by  the  writers  but  is  a  summary  of 
several  years  observations  made  by  them  in  plum  orchards  in  all 
sections  of  the  state  and  is  supplemented  by  data  gathered  from  indi- 
vidual growers  who  have  experimented  with  plum  grafting  for  pollina- 
tion or  other  purposes.  In  many  cases,  it  was  possible  to  locate  large 
numbers  of  the  same  combination  of  varieties  in  several  sections  of  the 
state.  In  others,  however,  it  was  possible  to  locate  only  one  or  two 
trees  of  a  given  combination  in  one  section.  However,  the  latter  were 
generally  deemed  of  sufficient  importance  to  be  included  in  this  report.' 

In  some  instances  the  findings  may  be  contradictory,  because  of 
many  variable  factors.  The  data  in  some  cases  may  not  be  in  accord 
with  the  findings  of  certain  individuals  but  this  is  to  be  expected  on 
account  of  the  many  variable  factors  such  as  tree  age,  vigor,  soil,  and 
moisture  conditions,  that  enter  into  grafting.  At  best,  the  data  pre- 
sented can  be  but  a  guide  to  the  prospective  fruit  tree  grafter  in  show- 
ing him  the  possibilities  of  a  successful  graft  union  and  ultimate  new 


Bui>.  438]        GRAFTING  AFFINITIES  WITH  REFERENCE  TO  PLUMS  5 

top.  Obviously,  it  has  been  impossible  to  cover  the  entire  field.  No 
doubt  many  growers  have  had  experiences  with  plum  grafting-  that 
would  be  of  much  value  in  a  publication  such  as  this.  It  is  hoped  that 
such  individuals  will  inform  the  writers  of  these  observations  so  they 
may  be  incorporated  in  later  reports. 

The  data  presented  here  refer  to  cases  where  grafting  has  been 
practiced  in  main  frame-work  branches  in  both  young  and  old  trees. 
.It  does  not  refer  to  nursery  budding  or  grafting.  In  view  of  the  fact 
that  many  varieties  have  not  been  worked  over  until  recent  years,  it 
is  impossible  to  draw  definite  conclusions  in  all  cases.  Budding  in  the 
nursery  row  and  grafting  in  the  frame- work  branches  or  trunk  some- 
times bring  opposite  results.  For  example,  the  Diamond  plum  when 
budded  in  the  nursery  row  on  peach  root  frequently  makes  a  brittle 
union,  causing  considerable  breakage  during  the  earlier  years  in  the 
orchard.  When  grafted  into  the  scaffold  branches  of  peach  trees,  how- 
ever, only  a  small  amount  of  breakage  occurs,  despite  the  fact  that  the 
union  is  enlarged.  Those  branches  which  survive  the  first  few  years 
always  make  a  satisfactory  top. 

A  bad  constriction  often  appears  at  the  point  of  union.  Frequently, 
this  does  not  seem  to  have  any  deleterious  effect  upon  the  growth  of 
the  scion  or  the  production  of  fruit.  Unless  actual  breakage  occurs 
between  stock  and  scion,  reports  will  be  given  in  some  instances  where 
congeniality  apparently  exists  between  a  given  pair  of  varieties. 
Further,  although  a  certain  variety  as  a  scion  may  stick  to  the  stock, 
for  a  number  of  years,  it  cannot  be  classed  as  a  commercial  success 
unless  good  production  is  secured. 

In  presenting  the  data,  each  variety  will  be  considered  separately 
and  the  behavior  of  the  various  other  varieties  when  top-worked  on  it 
will  be  discussed.  The  data  in  condensed  form  will  be  found  at  the 
end  of  this  publication. 


BEHAVIOR    OF    VARIOUS    PLUM    VARIETIES    AS    STOCKS 

Apex. — The  Apex  plum  has  been  worked  over  to  many  other 
varieties.  Those  which  appear  to  do  well  on  it  are  Beauty,  Burbank, 
Climax,  Duarte,  Formosa,  Santa  Rosa,  and  Satsuma.  On  the  other 
hand,  three  varieties  seem  to  give  successful  results  in  some  cases  and 
failure  in  others;  namely,  Gaviota,  Kelsey,  and  Wickson.  In  view  of 
these  results,  placing  these  varieties  on  Apex  is  questionable.  All  of 
the  varieties  mentioned  above  belong  to  the  class  known  as  the 
Japanese  plums  and  seem  to  segregate  themselves  into  two  groups, 
one  including  the  varieties  which  will  do  well  when  grafted  on  Apex, 


b  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

and  the  other  including  those  varieties  which  give  uncertain  results 
when  used  as  the  scion. 

Many  attempts  have  been  made  to  get  the  European  plums  to 
grow  on  the  Apex.  Of  the  many  varieties  used,  all  have  given  nega- 
tive results.  The  newly  set  scions  often  start  out  vigorously  in  growth 
but  soon  fail  to  increase  much  in  size.  The  European  varieties  which 
have  acted  in  this  manner  are  California  Blue,  Clyman,  Diamond, 
French  prune,  Giant,  Grand  Duke,  Hungarian,  President,  Sugar 
prune,  Tragedy,  Quackenboss,  Imperial  prune,  Robe  de  Sergeant,  and 
Standard  prune. 

From  the  foregoing  statements,  it  is  apparent  that  the  Apex  will 
probably  unite  well  with  most  of  the  common  Japanese  varieties 
excluding  Gaviota,  Kelsey  and  Wickson,  but  seems  to  lack  affinity  for 
all  the  European  plums  which  have  been  tried  on  it,  including 
shipping  and  drying  varieties. 

Beauty. — What  has  already  been  stated  regarding  the  behavior  of 
the  various  Japanese  and  European  plums  on  Apex  can  be  repeated 
for  the  Beauty  as  a  stock.  However,  while  three  Japanese  varieties 
were  mentioned  as  giving  questionable  results  when  grafted  on  Apex — 
namely,  Wickson,  Kelsey,  and  Gaviota — a  fourth,  the  Burbank,  can 
be  added  to  the  list  for  Beauty.  Apparently,  this  variety  will  grow 
well  on  the  Beauty  under  a  certain  set  of  conditions,  but  will  not  do 
well  under  another. 

After  a  year's  thrifty  growth  on  the  Beauty,  the  Burton  prune 
seems  to  be  showing  less  vigor  during  the  second  season.  It  appears 
as  though  fruit  wood  is  being  formed  at  the  expense  of  wood  growth. 
This  variety  will  doubtless  fall  into  the  same  category  as  the  rest  of 
the  European  types. 

Burbank. — This  variety  appears  to  be  an  unsatisfactory  stock. 
Although  many  attempts  have  been  made  to  top-work  the  Burbank, 
the  only  plums  that  have  proved  satisfactory  in  this  respect  are  the 
following  Japanese  varieties:  Apex,  Beauty,  Duarte,  Santa  Rosa, 
Satsuma,  Formosa,  and  Wickson,  the  last  two  giving  questionable 
results  in  a  few  cases.  The  Burton  prune  and  all  of  the  European 
varieties  mentioned  as  failures  when  tried  on  Apex  have  given  poor 
results  on  the  Burbank  also. 

Burton  Prune. — Owing  to  the  fact  that  this  variety  is  of  recent 
introduction  into  California,  no  data  as  to  the  behavior  of  other 
varieties  on  it  are  available. 

California  Blue  (Vaeaville). — Although  other  plum  varieties, 
including  Japanese  and  European,  have  been  grafted  frequently  on 
this  plum  in  both  the  Vaeaville  and  foothill  regions,  experience  has 


BUL.  438]        GRAFTING  AFFINITIES  WITH   REFERENCE  TO  PLUMS  7 

shown  it  to  be  an  unsatisfactory  stock  for  nearly  every  plum.  Despite 
the  fact  that  the  newly  set  scion  will  often  start  growth,  it  apparently 
is  not  compatible  with  the  California  Blue  stock  and  soon  commences 
to  show  weakness  in  vigor,  eventually  ceasing  growth,  and  dying. 
Of  twenty-five  or  more  commercial  varieties  tried  with  it,  none  has 
been  successful.  From  this  it  is  evidently  safe  to  conclude  that  no 
plum  should  be  grafted  on  the  California  Blue. 

Climax. — With  the  exception  of  the  Burbank,  which  makes  a 
doubtful  union,  the  Climax  seems  to  make  a  satisfactory  stock  for 
practically  all  Japanese  plums,  including  Apex,  Beauty,  Climax, 
Duarte,  Formosa,  Gaviota,  Kelsey,  Santa  Rosa,  Satsuma,  and  Wickson. 
The  Climax,  on  the  other  hand,  has  proved  unsatisfactory  for  all  of 
the  European  plums  which  have  been  worked  on  it,  including  all  the 
varieties  mentioned  above  as  having  been  grafted  on  the  Apex. 
Although  many  of  the  plums  in  this  class  will  unit  and  stick  to  the 
Climax  for  several  years,  the  growth  made  is  far  from  that  required 
to  set  a  good  crop.  For  instance,  Tragedy  on  the  Climax  has  made 
but  about  four  feet  of  growth  in  as  many  years. 

(Ill man. — This  variety  is  a  satisfactory  stock  for  all  Japanese  and 
European  plums  grafted  on  it,  except  the  California  Blue.  Because 
of  its  compatibility,  and  of  its  suitability  for  both  stock  and'  scion,  it 
is  frequently  used  as  an  intermediate  stock  in  those  cases  where  a 
direct  union  is  impossible  between  certain  varieties  (fig.  1).  Those 
varieties  which  have  made  compatible  unions  with  the  Clyman 
include  the  following  Japanese  plums :  Apex,  Beauty,  Burbank, 
Climax,  Duarte,  Formosa,  Gaviota,  Kelsey,  Santa  Rosa,  Satsuma  and 
Wickson,  and  the  European  plums  Diamond,  French  prune,  Giant, 
Grand  Duke,  Hungarian,  President,  Sugar  prune,  Tragedy,  Quacken- 
boss.  Imperial  prune,  Robe  de  Sergeant  prune  and  Standard  prune. 
The  President  makes  a  slow  growth  during  the  first  season. 

Diamond. — The  Diamond,  like  the  Clyman,  lends  itself  to  top- 
working  with  other  varieties.  In  addition  to  the  varieties  listed  as 
successful  on  the  Clyman,  the  Burton  prune  should  be  added  as  also 
being  successful  on  Diamond.  Here  again,  the  only  plum  variety 
which  does  not  seem  to  do  well  on  it  is  the  California  Blue.  The 
Diamond  lias  one  drawback,  however;  the  bark  is  thick,  especially  on 
old  trees  and  is  sometimes  difficult  to  graft,  forming  a  poor  union; 
With  old  trees,  success  can  be  secured  by  cutting  back  severely  into 
old  wood  and  then  grafting  into  the  new  growth  during  the  following 
winter  season.  This  cutting  is  generally  done  about  five  feet  from  the 
ground  with  trees  around  twelve  years  of  age.  With  older  trees, 
however,  the  cuts  are  generally  made  higher  up. 


8  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Duarte. — This  variety  is  one  on  which  but  few  plums  do  well. 
Twenty-five  plum  varieties  are  known  to  have  been  tried  on  it,  only 
six  being  successful :  Apex,  Beauty,  Climax,  Formosa,  Santa  Rosa, 
and  Satsuma,  all  of  them  Japanese  types.  Other  Japanese  varieties 
such  as  Gaviota,  Kelsey  and  Wickson  appear  to  make  a  good  union, 
but  the  tops  make  little  growth  and  lack  vigor  and  production.     The 


Fig.  1. — A  tree  made  up  of  peach  root,  Clyman  plum  as  intermediate  stock 
and  Grand  Duke  plum  as  top.  The  Clyman  finds  much  use  as  a  stock  for  such 
purposes  where  certain  varieties  cannot  be  worked  directly  on  other  varieties 
or  species.     The  Grand  Duke  top  is  entering  the  third  season's  growth. 


BUL.  438]        GRAFTING  AFFINITIES  WITH  REFERENCE  TO  PLUMS  9 

Burbank  falls  into  the  questionable  class,  making  a  good  growth  on 
some  occasions  but  only  mediocre  progress  on  others.  Evidently,  none 
of  the  European  types  will  make  a  good  union  with  the  Duarte  as  the 
stock,  if  one  judges  from  the  behavior  of  some  fourteen  varieties 
which  have  been  grafted  on  it. 


^#s> 


mffism 


Fig.  2. — Formosa  grafted  over  to  Kelsey.     Tree  making  excellent  growth 
and  producing  splendid  crops. 


Formosa, — On  the  Formosa,  all  of  the  common  Japanese  varieties 
except  Santa  Rosa  and  Wickson  appear  to  do  well  (fig.  2).  Observa- 
tions have  shown  these  two  to  behave  peculiarly.  In  some  cases,  the 
new  tops  are  satisfactory,  while  in  others  the  scions  make  but  little 


10 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT    STATION 


growth.  Most  of  the  European  varieties  which  have  been  tried  on 
Formosa  appear  to  make  a  satisfactory  union  during  the  early  life  of 
the  graft,  but  the  tops  soon  become  dwarfed  (fig.  3),  are  short-lived 


<$* 


«*  ;twt- 


»**•* 


Fig.  3. — Diamond  on  Formosa.     A  small  weak  top  after  making  six  years 
growth.     A  poor  commercial  tree. 


and  set  little  fruit,  the  latter  generally  maturing  about  a  week  to  ten 
days  earlier  than  normal.  This  characteristic  of  early  maturing  is 
especially  pronounced  on   California  Blue,   Diamond,   Grand   Duke, 


BUL.  438]        GRAFTING  AFFINITIES  WITH  REFERENCE  TO  PLUMS  11 

and  President  and  is  of  course  an  advantage.  Unfortunately,  how- 
ever, the  European  top  eventually  proves  to  be  unsatisfactory  since 
it  lacks  affinity  with  the  Japanese  stock.  It  is  impossible  to  state  how 
successful  the  Burton  prune  will  prove  on  Formosa.  Two-year-old 
grafts,  the  oldest  found,  are  making  an  excellent  growth,  though  the 
union  does  not  seem  to  be  secure.  In  the  light  of  this  fact,  it  is 
probable  that  the  Burton  will  fall  into  the  same  category  as  other 
European  varieties  for  top-working  the  Formosa. 

French  Prune. — The  success  attained  in  grafting  some  twenty-five 
varieties  of  plums  on  the  French  prune  indicates  congeniality  of  this 
stock  with  all  the  common  plums,  both  Japanese  and  European  types, 
except  possibly  the  California  Blue.  In  fact,  some  have  used  the 
French  prune  as  an  intermediate  stock  between  varieties  which  do  not 
unite  directly.  The  Japanese  varieties  successful  on  the  French 
prune  are  Apex,  Beauty,  Climax,  Duarte,  Formosa,  Gaviota,  Kelsey, 
Santa  Rosa,  Satsuma  and  Wickson;  the  European  varieties,  Burton 
prune,  Clyman,  Diamond,  Giant,  Grand  Duke,  Hungarian,  President, 
Sugar  prune,  Tragedy,  Quackenboss,  Imperial  prune,  Robe  de 
Sergeant  prune  and  Standard. 

Gaviota. — Of  all  the  Japanese  varieties  of  plums  which  have  been 
grafted  on  the  Gaviota  only  the  Kelsey  seems  questionable  for 
commercial  success.  The  others,  including  Apex,  Beauty,  Climax, 
Duarte,  Formosa,  Santa  Rosa  and  Wickson,  appear  to  give  good 
results.  How  the  Burbank  would  behave  on  Gaviota  cannot  be  stated, 
since  it  was  impossible  to  locate  this  combination.  Although  some 
fourteen  European  varieties  have  been  grafted  on  the  Gaviota,  none 
can  be  considered  a  success.  It  does  not  appear  safe,  therefore,  to 
attempt  to  change  the  Gaviota  plum  over  to  any  European  type. 

Giant. — What  has  already  been  stated  about  the  French  prune  as 
a  stock  applies  equally  as  well  to  the  Giant.  All  varieties  tried  on  it 
have  been  successful  except  California  Blue,  which  is  apparently  the 
only  variety  not  congenial  with  it.  The  Giant  has  shown  itself  to  be 
a  good  all-around  stock  for  grafting  purposes.  It  will  unite  well  with 
all  the  varieties  presented  under  the  discussion  of  the  French  prune 
as  a  stock. 

Grand  Duke. — Although  the  bark  on  old  Grand  Duke  trees  is  a 
little  harder  to  work,  the  two  varieties.  Grand  Duke  and  Giant,  fall 
into  the  same  class  for  grafting  purposes.  With  the  exception  of  the 
President  all  varieties  listed  as  successful  on  the  Giant  may  be  used 
to  equal  advantage  on  the  Grand  Duke. 

Hungarian. — A  discussion  of  this  variety  as  a  grafting  stock  is 
unnecessary,   because  it  behaves  similarly  to  the   Grand  Duke   and 


12  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 

Giant  as  discussed  above.  However,  as  was  the  case  with  the  Grand 
Duke  as  a  stock,  there  seems  to  be  some  question  as  to  the  advisability 
of  working  the  President  on  it.  Good  results  have  been  secured  in 
some  cases  and  only  a  mediocre  outcome  in  others.  In  the  latter  case, 
the  union  is  poor  and  the  graft  short-lived.  All  other  varieties  appear 
to  be  doing  satisfactorily  on  the  Hungarian,  excluding,  of  course,  the 
California  Blue,  the  behavior  of  which  on  other  varieties  has  already 
been  mentioned. 

Kelsey. — All  of  the  common  Japanese  varieties  have  given  good 
results  on  the  Kelsey  with  one  possible  exception — namely,  the  Bur- 
bank.  This  variety  apparently  is  less  safe  to  use  than  the  other 
Japanese  plums,  for  it  makes  a  short,  slow  growth.  Of  the  European 
varieties  tried  on  Kelsey,  all  have  been  failures.  It  does  not  seem 
safe,  therefore,  to  attempt  to  grow  any  European  type  of  plums  on 
the  Japanese  variety  Kelsey. 

President. — Little  need  be  said  of  this  variety  as  a  stock  for  other 
plums.  Save  the  California  Blue,  all  plums  tried  on  it  have  been 
successful,  the  list  including  practically  all  of  the  important  varieties. 

Quackenboss. — The  few  varieties  of  plums  that  have  been  grafted 
on  Quackenboss  have  given  satisfactory  results.  Among  the  Japanese 
types,  Apex,  Beauty,  Burbank,  Climax,  Duarte,  Formosa,  Gaviota, 
Kelsey,  and  Santa  Rosa  have  proved  successful ;  among  the  European, 
Hungarian,  Imperial  prune  and  Robe  de  Sergeant  prune.  The 
behavior  of  President  on  Quackenboss  is  questionable,  some  growers 
getting  good  results  and  others  not. 

Imperial  and  Robe  De  Sergeant  Prunes. — Additional  observations 
must  be  made  before  it  is  possible  to  give  definite  data  regarding  the 
behavior  of  other  plums  on  these  two  varieties. 

Santa  Rosa. — The  Kelsey  is  the  only  Japanese  plum  which  cannot 
be  classed  as  doing  well  on  the  Santa  Rosa.  Although  it  is  not  a  total 
failure,  the  Kelsey  generally  lacks  in  vigor  when  growing  on  Santa 
Rosa.  Many  European  varieties  have  been  tried  on  the  Santa  Rosa, 
all  of  which  have  responded  poorly,  growth  and  fruitfulness  con- 
sidered. From  the  fact  that  California  Blue,  Clyman,  Diamond, 
French  prune,  Giant,  Grand  Duke,  Hungarian,  President,  Sugar 
prune,  Tragedy,  Quackenboss,  Imperial  prune,  Robe  de  Sergeant  prune 
and  Standard  prune  have  all  been  given  a  trial  on  Santa  Rosa  and 
have  offered  little  in  the  way  of  a  new  top,  it  appears  as  though  the 
Santa  Rosa  should  not  be  worked  over  to  any  of  the  European  types. 

Satsuma.  Since  the  behavior  of  the  plum  varieties  is  exactly  the 
same  on  Satsuma  and  Santa  Rosa,  nothing  additional  need  be  said 
regarding  the  former  for  stock  purposes. 


Bui,.  438]      grafting  affinities  with  reference  to  plums  13 

Standard. — This  variety  has  not  as  yet  been  worked  over  to  many 
other  plums.  All  varieties  that  have  been  used  for  such  purposes, 
however,  have  given  satisfactory  results.  Apex,  Beauty,  Duarte, 
Formosa,  Gaviota,  and  Santa  Rosa  are  the  Japanese  varieties  which 
have  been  tried,  while  French  prune,  President,  Sugar  prune,  Imperial 
prune,  Robe  de  Sergeant  prune,  Burton  prune,  and  Quackenboss  make 
up  the  European  plum  list.  The  President  makes  a  somewhat  bulky 
union  and  the  growth  is  not  as  satisfactory  as  that  made  by  some  of 
the  other  varieties. 

Sugar  Prune. — This  variety  has  shown  itself  to  be  a  good  all- 
around  stock  for  all  plums  except  California  Blue,  which  is  unsatis- 
factory on  it.  In  fact,  the  discussion  given  under  the  French  prune 
as  a  stock  applies  equally  well  to  the  Sugar  prune. 

Tragedy. — Tragedy  has  made  a  good  union  with  all  plums  tried  on 
it  except  the  California  Blue,  especially  if  grafted  over  while  the  tree 
was  ^oung.  Old  trees  have  presented  some  difficulty  because  of  the 
thick  bark.  On  the  Tragedy,  as  on  the  French  and  Sugar  prunes 
both  Japanese  and  European  plums  do  well. 

Wickson. — Most  of  the  common  Japanese  varieties  of  plums  have 
been  grafted  on  Wickson,  all  of  them  evidently  giving  satisfactory 
results  except  the  Kelsey,  which  is  more  or  less  unreliable  in  its 
behavior.  Apex,  Beauty,  Climax,  Duarte,  Formosa,  Gaviota,  Santa 
Rosa  and  Satsuma  are  among  those  varieties  which  adapt  themselves 
well  to  the  Wickson  stock.  It  is  not  safe,  however,  to  graft  any  of 
the  European  types  on  Wickson,  for  not  a  single  one  of  the  many 
varieties  that  have  been  tried  has  proved  successful. 

Peaches  as  Stock  for  Plums. — The  peach  forms  a  satisfactory  stock 
for  all  Japanese  varieties  of  plums  except  the  Climax  and  is  com- 
monly so  used  in  the  lighter  soils.  The  following  European  varieties 
apparently  make  a  good  union  and  satisfactory  growth  when  top- 
worked  on  most  peaches,  although  the  unions  with  certain  peach  seed- 
lings may  sometimes  be  questionable :  French  prune,  Giant,  Hun- 
garian, President,  Tragedy,  Quackenboss.  President  on  Lovell  peach 
has  given  poor  results.  The  Grand  Duke  should  be  added  to  the  above 
list  even  though  many  have  often  recommended  against  grafting  this 
combination  (fig.  4).  The  plum  top  seems  to  grow  much  faster  than 
the  peach  stock,  forming  a  bad  constriction  at  the  union,  but  the  vigor 
and  production  of  this  variety  is  generally  satisfactory.  This  is  true 
even  though  a  small  amount  of  breakage  may  often  occur  during  the 
early  life  of  some  of  the  grafts.  Breakage,  however,  does  not  always 
occur,  for  there  is  a  large  orchard  near  Penryn  which  consists  of 
Giants  and  Grand  Dukes  grafted  to  peach  seedlings.    A  single  branch 


14 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT    STATION 


has  yet  to  break  at  the  union  of  either  of  these  varieties  with  the 
peach,  despite  the  fact  that  the  grafts  are  several  years  of  age.  In 
practically  every  case,  the  diameter  of  the  Grand  Duke  scion  directly 


Fig.  4. — Peach  seedling  grafted  over  to  Grand  Duke.  Although  the  plum  is 
outgrowing  the  peach,  the  trees  in  the  orchard  are  making  splendid  growth 
and  producing  excellent  crops.  Notwithstanding  the  constriction  at  the  union, 
no  breakage  has  occurred  on  any  of  the  trees. 

above  the  union  is  nearly  twice  that  of  the  peach  stock  directly  below 
it.  The  Giant,  on  the  other  hand,  has  made  a  perfect  union  with  the 
peach,  there  being  no  constriction.     The  Diamond  has  been  grafted 


BUL.  438]        GRAFTING  AFFINITIES  WITH  REFERENCE  TO  PLUMS  15 

on  peach  to  quite  an  extent,  but  the  union  is  somewhat  brittle  for  a 
few  years  and  a  small  amount  of  breakage  generally  occurs.  However, 
those  grafts  which  survive  the  first  few  years  make  a  splendid  growth 
and  form  a  satisfactory  top.  This  is  not  always  the  case  with  nursery 
budded  trees.    Here  considerable  breakage  frequently  occurs. 

What  has  just  been  stated  regarding  the  type  of  growth  made  by 
the  Grand  Duke  on  peach  seedling  applies  equally  to  the  Burton 
prune.  Though  this  variety  outgrows  the  peach  stock,  there  is  prac- 
tically no  loss  from  breakage  at  the  union. 

The  external  appearance  of  the  union  made  by  California  Blue  on 
peach  appears  satisfactory,  but  the  plum  often  dies  back  from  the  tip, 
thus  indicating  possible  lack  of  congeniality  between  the  plum  top 
and  peach  stock. 

Most  of  the  prunes,  other  than  French  and  Burton,  including 
Imperial,  Robe  de  Sergeant,  and  Sugar,  fail  to  make  successful  unions 
when  worked  on  peaches.  It  appears  as  though  certain  varieties  of 
peaches  are  successful  but  others  not  satisfactory.  Before  definite 
recommendation  regarding  the  best  varieties  for  such  purposes  can 
be  made,  additional  observations  will  be  necessary. 

In  view  of  the  fact  that  some  plums  cannot  be  worked  directly  on 
the  peach,  many  growers  have  practiced  double-working,  placing  a 
plum  variety  such  as  Clyman,  on  the  peach  to  serve  as  intermediate 
stock.  Many  such  instances  are  giving  satisfactory  results  in  the 
Sierra  foothill  region. 

Myrobalan  Plum  as  Plum  Stock. — Though  this  stock  is  generally 
used  in  the  nursery  for  plum  propagation,  it  has  been  used  to  a  slight 
extent  only  for  top-working  purposes.  Excepting  the  Robe  de 
Sergeant  prune,  for  which  it  is  quite  difficult  to  find  a  satisfactory 
stock,  the  Myrobalan  has  proved  a  success  with  all  varieties  that  have 
been  worked  on  it. 

Almonds  as  Plum  Stock. — Some  plums  appear  to  do  well  on  the 
almond,  while  others  do  not.  As  far  as  can  be  learned,  those  plums 
that  have  been  tried  and  that  appear  to  be  satisfactory  are  Apex, 
Duarte,  and  Formosa  among  the  Japanese  varieties,  and  Clyman, 
French  prune,  Hungarian,  President,  Sugar,  Tragedy,  and  Standard 
among  the  European  types.  It  is  questionable  whether  or  not  the 
Sugar  should  be  included  in  the  list  above  because  of  some  results 
secured  in  the  Winters  section,  where  this  variety  was  grafted  on 
Eureka,  Ne  Plus  Ultra,  Nonpareil,  Drake,  Peerless,  and  I.X.L. 
almonds.  Practically  all  of  the  grafts  on  the  last  four  varieties  died 
within  three  years.  On  the  other  hand,  those  on  Eureka  and  Ne  Plus 
Ultra  were  still  in  good  condition  after  growing  seven  years. 


16 


UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION 


Grafting  Burbank,  Burton,  Climax,  California  Blue,  Diamond, 
Gaviota,  Kelsey,  Santa  Rosa,  Wickson,  Imperial  and  Robe  de  Sergeant 
on  almonds  is  still  questionable  (fig.  5).  With  additional  observations, 
however,  it  may  be  possible  to  class  some  of  these  as  safe,  for  many  of 
them  have  given  very  good  results  under  certain  conditions.  The 
California  Blue  and  Robe  de  Sergeant,  however,  appear  to  be  total 
failures. 


Fig.  5. — On  certain  types  of  almonds  the  Burton  prune  does  not  make  a 
perfect  union  as  this  illustration  indicates. 

Splendid  results  have  been  secured  with  the  Burton  prune  on 
Texas  almond.  Where  this  plum  has  been  grafted  on  a  miscellaneous 
collection  of  almond  seedlings,  however,  about  25  per  cent  made  per- 
fect, 50  per  cent  fairly  good,  20  per  cent  indifferent,  and  5  per  cent 
poor  unions. 


BUL.  438]        GRAFTING  AFFINITIES  WITH  REFERENCE  TO  PLUMS 


17 


As  far  as  the  observations  have  been  carried,  it  appears  that  some 
plum  varieties  can  be  worked  successfully  on  only  certain  varieties 
or  types  of  almonds. 

Apricots  as  Plum  Stock. — Many  attempts,  most  of  which  have 
ended  in  failures,  have  been  made  to  graft  plums  on  apricots.     Some 


i 


Fig.  6. — A  three-year-old  Burton  prune  graft  on  apricot  stock.     Note  the 
splendid  growth  made  by  the  prune  top. 

growers,  however,  are  well  pleased  with  results  from  grafting  Clyman, 
French,  Giant,  Kelsey,  Satsuma,  Sugar,  Tragedy,  Wickson,  Quacken- 
boss,  Imperial,  and  Standard  on  the  apricot.  It  should  be  mentioned, 
however,  that  only  rarely  are  any  of  the  plums  as  satisfactory  on  the 
apricot  as  on  some  of  the  other  stocks.     In  fact,  it  is  questionable 


18  UNIVERSITY  OF   CALIFORNIA EXPERIMENT    STATION 

whether  the  prunes  should  be  placed  in  the  list  above  because  of  the 
poor  results  given  in  many  cases  when  they  were  top-worked  on 
apricots.  However,  there  are  many  cases  where  the  Imperial  and 
French  prunes  have  given  splendid  results  on  the  apricot,  despite  the 
fact  that  extreme  care  had  to  be  exercised  in  supporting  the  grafts 
during  the  first  few  years.  In  practically  every  instance  the  prune 
has  outgrown  the  apricot,  forming  a  rather  large  constriction  at  the 
union.     The  Burton  prune  has  given  about  the  same  results  as  the 


Fig.  7. — When  prunes  are  topworked  on  apricots  the  prune  top  generally 
outgrows  the  apricot  at  the  point  of  union.  However,  this  does  not  seem  to 
affect  the  top  growth  in  any  manner  whatever. 

Imperial  and  French.  Although  a  constriction  is  evident,  the  prune 
top  is  making  satisfactory  growth  where  top-worked  on  the  Royal 
apricot  and  as  yet  no  breakage  has  occurred  (figs.  6  and  7). 

Plums  as  Stocks  for  Peaches,  Apricots,  Almonds,  and  Myrobalan 
Plum  Seedlings. — Although  many  varieties  of  plums  have  been  grafted 
on  such  fruits  as  peaches,  apricots,  almonds,  and  Myrobalan  plum 
seedlings,  a  considerable  amount  of  top-working  has  also  been  prac- 
ticed with  these  various  fruits  on  standard  varieties  of  plums.  The 
results  of  such  attempts  can  be  dismissed  by  the  statement  that  peaches 
and  almonds  generally  fail  to  grow  on  plums,  that  apricots  have  not 
been  successful  to  any  extent  where  tried,  and  that  the  Myrobalan 
plum  seems  to  thrive  well,  particularly  on  the  European  types. 


Bl'L.  438]        GRAFTING  AFFINITIES  WITH    REFERENCE  TO   PLUMS 


19 


i    1,1a, 

3'    g  S  O 


2-  S.  5 

5,  2  ^ 

f  3  8 

5-  g  3 

g  §  jS 

-  2:  p 

£  5  a-. 

««  R  £ 
a 


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p 


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DQOQ0DOQDOODOQ0Q0E 

cococococococococccodcocox 

Apex 

woiKaiaiDCK'uca 

COCOCOC0C0C0COCOCOCOdC0><jCO 

Beauty 

03  GO         KuDK  sg 

COCOCO         COCOOCOCOQdXOC0 

Burbank 

d  CO  OC  CO                               co 

CO   CO  CO          CO   Q          CO                      d 

Burton 

dai      d  d       cj  ci 

dddda^^Gd^Xddd 

California  Blue 

03  CO  CO         GO  GO  GO  CO  OD 

cococococococococo^ddcocc 

Climax 

d  co  co      cj  d      cc  d 

cocoxdcoddco^ddddd 

Clyrnan 

d  cc-  co      d  d      ^  d 

cococodcoddx^oddddd 

Diamond 

cococogogocccocogo 

C0C0COCOCOC0><jC0COCOdCOCOCO 

Duarte 

cogogogogococococo 

COCOCOCOCO^COCOCOCOdO50'32 

Formosa 

dcococodd      ^d 

cococodXddcocoddddd 

French 

cococococococococo 

cococoxcocodcococoddDO 

Gaviota 

d  co  go      d  d      x  jj» 

coco^dcoddcocoddddd 

Giant 

d  co  co      d  d      x  £* 

coxcodcoddcocoddddd 

Grand  Duke 

dcoco      ddcocod 

><jcocodcoddcocoddddd 

Hungarian 

dcococoddxcodX 

cococodcoddcocoddddd 

Imperial 

0  co  co      d  d  co  co  ^ 

COCOCOQCOCOdCOCOCOddDD 

Kelsey 

dcococodd      X  d 

OQcodcoddcocoddddd 

President 

dcococoddX^d 

cococodcoddcocoddddd 

Quackenboss 

dCQcocodd^ocod 

cococodcoddcocoddddd 

Robe  de 
Sergeant 

COCCCO         GO  ^  CO  CO  CO 

COCOCOCOCOQCOCOCOCOdCOCOCO 

Santa  Rosa 

CO  CO  CO         X   CO          CO  CO 

CQCOCOCOCOCOCOCOCOCOdCOCOCQ 

Sateuma 

dcoco^dd      dd  a 

cococodcoddcocoddddd 

Standard 

d  co  x  co  d  d       cod 

cococodcoddcocoddddd 

Sugar 

d  X  co      d  d      co  d 

cococodcoddcocoddddd 

Tragedy 

X  co  co       coco       coco       cococococoQdcococodDDD'  Wickson 


20  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 


SUMMARY 

1.  Three  factors  are  responsible  for  the  large  amount  of  grafting 
which  has  been  practiced  with  plums  during  recent  years.  These 
factors  are:  (a)  Effort  to  decrease  the  number  of  varieties,  (b) 
Necessity  of  changing  over  to  varieties  better  adapted  to  local  condi- 
tions, (c)  Importance  of  mixture  of  varieties  in  the  same  orchard 
to  effect  pollination. 

2.  The  large  amount  of  fruit  tree  grafting  that  has  been  practiced 
in  California  has  brought  to  light  much  information  concerning 
affinities  between  different  varieties  and  between  different  species  of 
fruit. 

3.  Peaches  and  almonds  generally  fail  to  grow  well  when  grafted 
on  plums. 

4.  None  of  the  European  varieties  of  plums  is  successful  when 
grafted  on  the  Japanese  types.  On  the  other  hand,  many  of  the 
Japanese  types  can  be  grafted  successfully  on  most  of  the  European 
varieties. 

5.  The  California  Blue  has  proved  to  be  a  failure  in  nearly  every 
case  where  it  has  been  used  either  for  stock  or  scion  purposes  in 
top-working. 

6.  Clyman,  Diamond,  French  prune,  Giant,  Sugar  prune,  and 
Tragedy  prune  make  excellent  stocks  for  all  other  varieties  worked  on 
them  except  the  California  Blue. 

7.  The  peach  tree  makes  a  good  stock  for  practically  all  Japanese 
plums  but  not  for  all  European  types. 

8.  Certain  varieties  of  plums  can  be  grafted  successfully  on  some 
almond  trees  while  others  cannot. 

9.  Only  a  few  varieties  of  plums  appear  to  do  well  when  grafted 
on  apricot  trees. 

ACKNOWLEDGMENTS 

The  writers  wish  to  express  their  appreciation  and  thanks  to  the 
man}'  fruit  growers  who  supplied  some  of  the  data  incorporated  in  this 
publication.  They  wish  especially  to  express  their  gratitude  to  Millard 
Sharpe  of  Vacaville  whose  assistance  and  cooperation  have  aided 
materially  in  the  completion  of  this  bulletin. 


lOrn-10,'27 


